By Kim Holdener, PharmD
High potassium (also known as high K) can be life threatening. People who are on dialysis are more likely to have high K than people with normal kidney function because K is removed from the body by the kidneys. High K is actually very rare in people with normal kidney function. There are often no symptoms when one's K is high, therefore, you might not know that you are in danger. People with life-threateningly high K need immediate treatment, usually through the emergency room.
If symptoms do occur with high K, they usually only occur when the K is very high, above 7 mmol/L. Symptoms that may occur include muscle weakness and changes in the conduction of signals through the heart. The changes in heart function can be detected with an electrocardiogram (also called an ECG or EKG). When changes in heart function due to high K can be detected by an ECG, it can lead to cardiac arrest (failure of the heart to pump) and death. The level of K that can cause cardiac arrest is different for each person.
In people who have heart changes detected by an ECG, calcium is given intravenously to protect the heart and prevent cardiac arrest. This treatment only lasts one hour at most. In the meantime, another treatment should be started to lower the K levels. Drug treatments can either eliminate K from the body or shift potassium from the blood stream into the cells. Shifting K into the cells is temporary. The most common medication used to shift K into the cells is insulin. Insulin should be given intravenously so it can act quickly. Intravenous glucose or dextrose is also given to prevent blood glucose levels from becoming too low from the insulin. This treatment takes effect within one hour but usually only lasts 4 hours at most. Sometimes sodium bicarbonate is given to shift K into the cells. However, this treatment usually works best in people who have low bicarbonate levels and who have kidney function.
In order to lower K to a safe level and keep it there, K must be eliminated from the body. There are several ways to remove K, but for dialysis patients the best way is with dialysis. K is removed from the body during each dialysis treatment. It is the fastest and most efficient way to lower K. Therefore, it is the treatment of choice for high K in a dialysis patient. There are two medications that can also be used to remove K from the body. Diuretics, such as furosemide (Lasix), given intravenously can be used to remove K through the urine. However, in patients who are on dialysis, diuretics do not work. The rate of elimination of K from the body with diuretics is also not very fast. Another medication that is used is sodium polystyrene (Kayexalate). This is a medication that is taken orally and removes K through the stool with a bowel movement. It takes up to 4 hours for it to take effect. Therefore, if quick K removal is needed due to life-threatening heart rhythm abnormalities, sodium polystyrene is not ideal. Most people do not like the taste of sodium polystyrene. This medication can also be given rectally as an enema.
The best way to treat high K is to prevent it! K enters the body through the foods we eat. Controlling the amount of K in the diet is absolutely essential for people on dialysis in order to avoid the life-threatening effects it can have on the body when it gets too high. It is much better to keep the K in your body at safe levels that can be removed with your regularly scheduled dialysis treatments. If you have any questions about foods that contain K and how to control K in your diet, be sure to talk to your dietician.
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